Apparatus for cooling and condensing gases



| LOTZSCH APPARATUS FOR COOLING AND CONDENSING GASES Feb. 11, 1969 FiledAug. 22, 1966 FIG. 2

INVIIINTOR LOTHAR LOTZSCH MflwWgM ATTORNEYS United States Patent3,426,446 APPARATUS FOR COOLIIE? AND CONDENSING GAS Liithar Lotzsch,Bad-Niederbreisig, Germany, asgignor to ETMA Maschinenfabrik G.m.b.H.Filed Aug. 22, 1966, Ser. No. 573,970 Claims priority, applicationGermany, Aug. 23, 1965,

51,456 US. C]. 34-77 Int. Cl. F26b 21 /14,- D061? 43/08 ABSTRACT OF THEDISCLOSURE This invention relates to an apparatus for condensing gases,which are evolved in dry-cleaning or washing machines, which use aliquid cleaning agent containing monofiuorotrichloromethane (CFCl and/0rdifluorodichloromethane (CF CI and/or l,2,2-trifiuorotrichloroethane Inknown dry-cleaning machines, solvents are used which includeperchloroethylene, ethylene trichloride and substances covered by thegeneric term naphtha. Solvents containing trifiuorotrichloroethane (CFCl-CF Cl) have also been used. Where such solvents are employed, anoff-take pipe for the fumes is required so that considerable amounts ofsolvent are lost. Special public regulations must be complied with whensuch plants are established in populated areas in order to avoid dangerto the inhabitants of the area. The compliance with these publicregulations adds substantially to the prime cost of the plant. The fumeswhich are evolved are also obnoxious and to some extent unhealthy to theoperators. Many of the above-mentioned disadvantages can be eliminatedwhen monofluorotrichloromethane is employed, particularly when thissolvent is recycled.

On the other hand, monofiuorotrichloromethane has a boiling point of+23.77 C. at 760 mm. mercury so that refrigerants having a much lowerboiling point must be used for cooling and condensing this solvent. Thesolvent could also be used with water but this would greatly prolong thebatch time so that the process would become uneconomical. A secondclosed cycle may be associated with the dry-cleaning machine and maycontain difl-uorodichloromethane having a boiling point of 29.80 C. at760 mm. mercury, or difluoromonochloromethane (CHF Cl) having a boilingpoint of 40.80 C., which is used as a refrigerant in such a manner thatthe CFCl vapor (gas) evolved in the cleaning drum is fed to anevaporator, which is cooled with CF CI or, e.g., CHF C1 and in which theheat exchange results in a condensation of the solvent CFCl One of theobjects of the invention is to provide an economically operatingapparatus for condensing gases of the liquid cleaning agent,particularly monofluorotrichloromethane. This is accomplished inaccordance with the invention by the provision of an air-circulatingconduit which extends :from the working chamber of the cleaning machineand gas-tightly through a condenser and discharges back into the workingchamber of the cleaning machine, and by the provision of an additionalcon- 11 Claims duit, which extends from the working chamber of thecleaning machine and communicates with the interior of the condenser.The arrangement according to the invention ensures that the solventvapors evolved as a result of the temperature rise of the liquidcleaning agent during the cleaning operation carried out in the drum arefed directly to the condenser. The vapors which are evolved after thedraining of the liquid cleaning agent and after the centrifuging of thecleaned material are also fed directly to the condenser. Thecondensation of the vapor in the condenser results in a reduction of theamount of vapor and of the pressure in the cleaning machine. The cleanedmaterial is free of solvent when the pressure has been reduced to theatmospheric pressure. By condensing of the vapors of the liquid cleaningagent in the condenser an underpressure is created in the condenser withrelation to the other 'parts of the cleaning machine. By this means thegas-air-mixture is fed to the condenser on a purely physical basis untilthe gas has been completely condensed and is therefore available for thenext cleaning operation.

According to a further inventive step the air or the airgas-rnixturepresent in the air-circulating conduit can, after draining of the liquidcleaning agent, be forced by a blower through said air-circulatingconduit and the working chamber of the cleaning machine, and a conduitfor discharging liquid agent can extend from the interior of thecondenser. Further, a heating element can be incorporated in theconduit, if desired. This measure enables an effective air supply to thecontents of the machine after the draining of the cleaning machine. Ifthe machine is heated, a particularly rapid formation of vapor willresult and the vapor will flow directly into the condenser, where thevapor condenses.

To obtain a closed cycle, another development of the invention providesthat the conduit for discharging condensed cleaning agents from thecondenser opens into a storage container for liquid cleaning agent.

To prevent a flow of uncondensed gases from the condenser into theinterior of the machine, a further embodiment of the invention comprisesa check valve which is incorporated in the conduit leading from theworking chamber of the machine into the interior of the condenser. Thischeck valve can preferably consist of a flap valve or the like which,according to a further feature of the invention, is automatically closedwhen the working chamber of the machine is opened.

In a further development of the invention, the interior of the condenseris connected by a pressure-equalizing conduit to the suction side of theair-circulating conduit, a shut-off valve being preferably incorporatedin the pressure-equalizing conduit.

Further, a still or distilling unit can succeed the storage tank and avapor conduit can lead from said still into the condenser, the latter inthis case being used not only for condensing the gases coming from theworking chamber but also the gases of the distilling circuit forcleaning the liquid cleaning agent.

The invention will now be explained more fully with reference to anembodiment which is shown by way of example in the drawing, in whichFIG. 1 is a diagrammatic general view of the apparatus according to theinvention and FIG. 2 a side elevation showing a portion of FIG. 1.

- In the drawing, a cleaning or washing machine 2 comprises a housing 1.A conduit 3 extends from the housing 1 through a condenser 4 and backinto the housing 1 of the washing or cleaning machine 2. An additionalconduit 6 extends from the interior 5 of the washing or cleaning machineand communicates with the interior of the condenser 4. Air may beintroduced into the conduit 3 and is forced by a blower 8 through theconduit 3 and the interior of the machine 2 when the liquid cleaningagent has been drained through a drain conduit 12 at the lowermost pointof the machine 2 and has been supplied in the direction of the arrow Pthrough a strainer 31 and a pump 32 to a storage tank 33. The strainer,pump and storage tank are connected in series. To accelerate theevaporation of the residual solvent contained in the cleaned material, aheating element 9 is incorporated in the condiut 3. The heating element9 may comprise an electric resistor or may be gas-fired.

Outlets 10, 11 for the distillate extend from the condenser 4 into aconduit 13, which leads to the solvent tank.

The conduit 6 which leads from the interior 5 of the machine 2 into theinterior 7 of the condenser 4 may incorporate a flap 34 which acts as acheck valve and is shut automatically as soon as the working chamber 5of the machine 2 is opened. In this condition, the flap prevents a flowof uncondensed gas from the condenser 4 back into the interior 5 of themachine 2.

As is shown in FIG. 1, the condenser 4 is sealed by two covers 14, 15,through which the conduit 3 extends in sealed relation. The condenser 4constitutes thus a double-walled container, which has an annular spacedefined on one side by the shell of the condenser and on the other sideby the conduit 3. The annular space contains evaporator tubes 18, whichmay be supplied with a refrigerant consisting of difiuorodichloromethane(CF- Cl or difluorochloromethane (C'I-IF Cl).

The process of cooling and condensing the solvent is carried out asfollows:

The liquid cleaning agent, which contains, e.g.,monofiuorotrichloromethane, is supplied from a filter through a conduit19 into the machine 2, which consists, e.g., of a drum-type machine. Asthe drum revolves, the liquid cleaning agent is heated to a temperatureof and above +23.77 C. by the friction at the drum shell and thematerial to be cleaned and by the constant circulation of the liquidcleaning agent through connecting conduits, the filter and a pump. Atthe said temperature, the monofiuorotrichloromethane boils under apressure of about 1.083 kg./crn. This superatmospheric pressure, whichreaches 4.171 kg./cm. at a temperature of +70 C., is undesired in thecleaning or washing process. For this reason, gas is forced throughconduit 6 into the interior 7 of the condenser 4, where the gascondenses on the refrigerant conduits 18. The resulting distillate isrecycled to the liquid cleaning agent tank through the outlets and 11and the condiut 13 so that the cleaning agent cycle is closed.

When the liquid cleaning agent has been removed from the machine 2through conduit 12 into the tank, which containsmonofiuorotrichloromethane, the cleaned material remains in the machine2. The circulating blower 8 is now started and the air from the bloweris heated in a heating element 9 to a temperature of about C. In thisway the residual solvent, such as monofluorotrichloromethane, which isstill contained in the cleaned material, is evaporated and introducedthrough conduit 6 into the condenser 4, where the gas is condensed. Thedistillate returns through outlets 10 and 11 and conduit 13 to the tankso that this cycle is closed, too.

As is apparent from FIG. 2, cleaning agent vapor, such asmonofluorotrichloromethane, which has been evolved in the still 35, isintroduced into the condenser 4 by a conduit 20, in which the vaporflows in the direction of arrow P The still is fed from the storagetank, and serves to distill the soiled liquid cleaning agent, asdesired. The gas which is supplied to the condenser 4 through conduit 20is condensed in condenser 4. The distillate is withdrawn through theoutlets 10, 11 and passed through conduit 13 to the tank. This isanother closed cycle. It is apparent from the above that thedistillation of soiled liquid washing agent, such asmonofluorotrichloromethane, can be carried out at the same time as thewashing of the material to be cleaned and does not result in an increaseof the superatmospheric pressure in the machine 2. On the other hand,soiled monofiuorotrichloroethane may be distilled independently of theprimary cleaning process. The cycle remains the same in this case.

The condenser 4 is provided with a connecting pipe 21 for a conduit 22,which is connected by a connecting pipe 23 to the air-circulatingconduit 3, which extends through the condenser 4. The conduit 22 is amanifold for an equalization of pressure. It connects all containers ofthe plant which contain monofiuorotrichloromethane and provides a meansfor the escape of air from the condenser 4, when the liquid cleaningagent is fill-ed into the working chamber 5. At this time a valve 36 isopened in the conduit 22. The conduit 22 also prevents an undesiredsuperatmospheric pressure in the spaces which containmonofluorotrichloromethane even when the supply of refrigerant to thecooling pipes 18 is discontinued. The vapors are then positivelycirculated in the equalizing conduits. As the conduit 22 discharges intothe suction side of the conduit 3, it further helps to create anunder-pressure in the condenser 4 which is necessary for the drawing inof the air-gas-mixture into the condenser.

What is claimed is:

1. Apparatus for condensing gases, which are evolved in dry-cleaning orWashing machines, which use a liquid cleaning agent containingmonofluorotrichloromethane (CFCI and/or difiuorodichloromethane (CF Cland/ or 1,2,2-trifluorotrichloroethane characterized by the provision ofan air-circulating conduit which extends from the working chamber of thecleaning machine and gastightly through a condenser having cooling pipestherein and discharges back into the working chamber of the cleaningmachine, and by the provision of an additional conduit, which extendsfrom the working chamber of the cleaning machine and communicates withthe interior of the condenser and a conduit for discharging condensedliquid cleaning agent from said condenser.

2. Apparatus according to claim 1, characterized in that the air or theair-gas mixture can, after draining of the liquid cleaning agent, beforced by a blower through said air-circulating conduit and the workingchamber of the cleaning machine, and the conduit for discharging liquidcleaning agent extends from the interior of the condenser.

3. Apparatus according to claim 1, characterized in that a heatingelement is incorporated in the air-circulating conduit.

4. Apparatus according to claim 1, characterized in that the conduit fordischarging condensed cleaning agent from the condenser opens into astorage container for liquid cleaning agent.

5. Apparatus according to claim 1, characterized by a check valve, whichis incorporated in the conduit leading from the working chamber of themachine into the interior of the condenser.

6. Apparatus according to claim 5, characterized in that the check valveconsists of a flap valve or the like.

7. Apparatus according to claim 6, characterized in that the valve isautomatically closed when the working chamber of the machine is opened.

8. Apparatus according to claim 1, characterized in that the interior ofthe condenser is connected by a pressure-equalizing conduit to thesuction side of the air-circulating conduit.

9. Apparatus according to claim 8, characterized in that a shut-offvalve is incorporated in the pressureequalizin-g conduit.

10. Apparatus accordin to claim 1, characterized in that a stillsucceeds the storage tank and a vapor conduit leads from said still intothe condenser.

11. Apparatus according to claim 1, characterized in that the coolingpipes of the condenser have passing therethrough a refrigerant having aboiling point below 0 C References Cited UNITED STATES PATENTS 2,011,0838/1935 Sando 3477 XR 2,019,011 10/1935 Johnson. 2,064,084 12/ 1936 Sando34-77 6 3,002,287 10/1961 Smith 3477 XR 3,163,028 12/1964 De Pas 3477 XRFREDERICK, L. MATTESON, JR., Primary Examiner.

HARRY B. RAMEY, Assistant Examiner.

US. Cl. X.R. 6818

